Modeling and Simulation of Semiconductor Optical Amplifier Dynamics for Telecommunication Applications

The semiconductor optical amplifier (SOA) is among the most promising optoelectronic devices to carry out all-optical information processing operations for future generations of telecommunication networks. Despite more than fifteen years of continuous investigation, the need for a deep understanding on the operation and performance of this sophisticated amplifier in the nonlinear regime has spurred the appearance of several models with their corresponding computer simulators. A set of criteria to simplify the selection of a single model/simulator to perform a particular operation in an optimal manner is therefore of great value for scientists and engineers. Therefore, in this contribution we propose a classification of SOA models aimed to help in this decision process. Such classification also considers a myriad of physical effects that the different models account for. These effects usually set the simulator's scope of applicability and therefore they are briefly discussed. Two different SOA models are then presented: a time-domain model and a frequency-domain model. Their complexity prevents analytical solutions and consequently, they have to be solved by means of numerical methods. Implementations of the corresponding nonlinear partial differential equation solvers, intended to be run on a personal computer, are then reviewed. They are based on the combined solution provided by an ordinary differential equations solver and analytic integrator of the propagation equations on a (1+1)-dimensional grid. A powerful simulator written in a graphical programming language around the time-domain model is then presented. The model is useful to analyze the interaction of the semiconductor amplifier with optical data sequences up to bit rates of 160 Gb/s (and even higher). This theoretical contribution is complemented with application examples showing the versatility of the developed computational tool in analyzing design problems commonly found nowadays within the optical telecommunications industry. In particular, two recently proposed structures to carry out wavelength conversion via cross-gain modulation are investigated. It is shown that they can be considered complementary structures, each one alleviating one of two deficiencies present in this kind of converters: poor extinction ratio and data-dependent patterning effects. A new structure is then put forward that combines the enhanced performance provided by each of the single structures. The improved quality of the new component functionality is demonstrated by means of wavelength conversion simulations at 10 Gb/s. Our theoretical investigation emphasizes the value of this software tool for the design and analysis of sophisticated integrated photonic circuits with active elements like SOAs.